A data storage system stores and retrieves information on behalf of one or more external host computers. A typical data storage system includes power supply circuitry, a storage processor, and a set of disk drives. The power supply circuitry provides power to the storage processor thus enabling the storage processor to load data into and retrieve data from the set of disk drives on behalf of the external host computers.
It is common for the electronic devices (e.g., integrated circuit components) forming the storage processor to require different voltages from the power supply circuitry, and for such devices to require the different voltages in a particular order when powering up in order to avoid damage. For example, suppose that the electronic devices for a particular storage processor use a 3.3 VDC signal for powering the input/output (I/O) circuitry and a 2.5 VDC signal for powering the core circuitry. In such a situation, the power supply circuitry may need to provide the 3.3 VDC signal first followed by the 2.5 VDC signal a short time later. Otherwise, the I/O circuitry will attempt to obtain power from the core circuitry and damage the core circuitry in the process.
One conventional data storage system, which is configured to power up in the manner described above, uses power supply circuitry having a power sequencing circuit consisting of discrete components. The discrete components operate to stagger delivery of the different voltages to the electronic devices of the storage processor (e.g., voltage dividers formed by discrete resistors, control circuits formed by discrete logic, timing circuits formed by individual resistors and comparators, etc.). Accordingly, the discrete components work to ensure that the I/O circuitry of electronic devices powers up before the core circuitry of the electronic devices thus preventing damage to the electronic devices.